The dominant mood in the first three acts of this terrifying play is that of rising hysteria and panic due to the apparent signs of witchery and of the devil that have descended on Salem. What is the most disturbing fact about this play is not the supposed devil worship that occurred, but the way in which the inhabitants of Salem are so caught up in hunting down those who are witches that they seem to lose all trace of reason and common sense. This contributes to the overall panicked and hysterical mood. Note how this is indicated in Act 1 by Mrs Putnam in the following conversation with Parris:

MRS. PUTNAM, glancing at Betty: How high did she fly, how high?PARRIS: No, no, she never flew – MRS. PUTNAM, very pleased with it: Why, it’s sure she did. Mr. Collins saw her goin’ over Ingersoll’s barn, and come down light as a bird, he says!

What is so concerning is the way in which Mrs Putnam will not hear anything that does not fit with her understanding of what has occurred, and also she is said to be "very pleased" with the fact that Betty has flown. This indicates the dominant mood of hysteria and panic that does so much to impact the behaviour of everybody, and with tragic consequences. The hysteria and panic is only something that increases in each act, until the final act, where it is clear that it is beginning to run its course.